Index Fossils
Answer Bank for items 1 through 5.
*fossils
*Index fossil
*Relative age
*widely distributed
*for only a short period of time/ briefly
*The fossil must be widely distributed and the organism must have existed only briefly
Copy and complete the numbered items for full credit. Sentences and answers equals 100%. (Answers only earns 25%)
Answer and explain the Lettered items for full credit.
Index Fossils 1. Rock layers that match can be given the same… 2. …… can help to match rocks of the same age, even when those rocks are far apart. 3. The relative age of a rock layer can be easily determined if it contains an ... 4. Two criteria for a useful index fossil are ……and …… 5a. If a fossil only occurs in one layer of rock it probably existed only… 5b. If a fossil is found in many different areas or locations it is considered… 6. The fossil shells of ammonites are found in many rock layers all over the world. 7. The ammonites in most of these rock layers are of a different kind base on changes in their shells. 8. Each kind of ammonite only existed during the time that its rock layer was forming. 9. The type of ammonite found in a rock layer can be used to determine its relative age. (Hint: A part of a sentence is not an explanation.) (Hint: Every pronoun must be preceded by its noun.) A. Explain why the brachiopod shells are NOT an index fossil. (Cite or use the figure below) B. Explain why the ammonite shells are an index fossil. (Cite or use the figure below) C. Explain what other fossil below (not an ammonite) could be an index fossil and why. (Cite or use the figure below.) Draw the figure below and note the two index fossils.
Answer Bank for items 1 through 5.
*fossils
*Index fossil
*Relative age
*widely distributed
*for only a short period of time/ briefly
*The fossil must be widely distributed and the organism must have existed only briefly
Copy and complete the numbered items for full credit. Sentences and answers equals 100%. (Answers only earns 25%)
Answer and explain the Lettered items for full credit.
Index Fossils
1. Rock layers that match can be given the same…
2. …… can help to match rocks of the same age, even when those rocks are far apart.
3. The relative age of a rock layer can be easily determined if it contains an ...
4. Two criteria for a useful index fossil are ……and ……
5a. If a fossil only occurs in one layer of rock it probably existed only…
5b. If a fossil is found in many different areas or locations it is considered…
6. The fossil shells of ammonites are found in many rock layers all over the world.
7. The ammonites in most of these rock layers are of a different kind base on changes in their shells.
8. Each kind of ammonite only existed during the time that its rock layer was forming.
9. The type of ammonite found in a rock layer can be used to determine its relative age.
(Hint: A part of a sentence is not an explanation.)
(Hint: Every pronoun must be preceded by its noun.)
A. Explain why the brachiopod shells are NOT an index fossil. (Cite or use the figure below)
B. Explain why the ammonite shells are an index fossil. (Cite or use the figure below)
C. Explain what other fossil below (not an ammonite) could be an index fossil and why. (Cite or use the figure below.)
Draw the figure below and note the two index fossils.
Ammonite
Brachiopod
Spiral
Trilobite
Trilobite
https://qrius.si.edu/watch/science-fmnh-trilobite-extinction#.VTGI29zF_sE